Relationship Between Compositions Of Urinary Nanocrystallites And The Types Of Urinary Stones

In this paper the composition, morphology and Zeta potential of crystallites of calcium oxalate, uric acid and magnesium ammonium phosphate stone formers were comparatively studied using X-ray diffraction (XRD), Fourier transform infrared (FT-IR) spectroscopy, nanoparticle size analyzer, scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Thirty random stone samples from lithogenic patients in Pearl River Delta area in recent years were investigated by XRD and FT-IR. The average diameter, size distribution, polydispersity index (PDI) and Zeta potential of urinary crystallites in lithogenic urines were investigated by nanoparticle size analyzer and were compared with those of healthy subjects.Calcium oxalate calculi usually coexisted with a little of uric acid and calcium phosphate. By contrast, the compositions of urine crystallites of the patients with calcium oxalate calculi were mainly uric acid, phosphate, calcium oxalate and so on. Most of them had sharp angularity with a particle size distribution ranging from tens of nanometers to tens of microns; and obvious aggregation was observed. The negative value of Zeta potential of urine crystallites in twenty stone formers (average value-5.92 mV) was less than that in twenty normal subjects (-12.9 mV). However, there was no obvious difference between the urine pH of stone formers (average pH=6.03) and that of normal subjects (average pH=5.92).The urine pH of uric acid stone formers was relatively low within the range of 4.8 to 5.7. The main constituent of urinary crystallites was uric acid. Their particle size distribution was highly uneven, ranging from several nanometers to several tens of micrometers, and obvious aggregation was observed. The Zeta potential of urinary crystallites in ten lithogenic patients was-6.02 mV, which being higher than that in ten normal subjects (-10.1 mV). After drug therapies (potassium citrate was taken), the urine pH value of the uric acid stone formers increased to 6.5 or so, and at this pH value most of the uric acid has changed to urate. Since the solubility of urate increased greatly than uric acid, the risk of the formation of uric acid stone reduced.A high pH value of 6.5 or more usually appeared in the urine of magnesium ammonium phosphate stone formers. The main component of urine microcrystalline was magnesium ammonium phosphate crystals with different crystal water such as monohydrate or hexahydrate. Magnesium ammonium phosphate crystals are mainly petal-shaped, crosswise shape. These microcrystalline have an uneven particle size distribution, a wider distribution range, and apparent aggregation. There is no significant difference of the zeta potential between the magnesium ammonium phosphate stone formers (mean-9.83 mV) and healthy control subjects (mean-10.74 mV).Calcium oxalate stone was the main composition of urinary stones in Pearl River Delta area, which accounting for 76.6%; and then were uric acid and calcium phosphate stones, which accounting for 16.7% and 6.7% respectively. There was obvious difference of urinary crystallites between stone formers and healthy subjects in average diameter, size distribution, polydispersity index (PDI) and Zeta potential. Calcium oxalate, uric acid, and calcium phosphate were the main constituents of urinary stones in Pearl River Delta area. The differences between stone formers and healthy subjects in average diameter, size distribution, PDI and Zeta potential of urinary crystallites made the healthy subjects difficult to form stone.The results in this paper showed that there was close relationship among stone components, urinary crystallites composition and urine pH. The study on the relationship between urine crystallites and urinary calculi components will be helpful for finding out the causes of urolithiasis and providing an important basis for the scientific prevention methods and reasonable treatments in clinic.